It is known to coat the edge of a workpiece as it is moving along in a direction generally parallel to its edge by flushing or spraying the edge with a liquid and then sucking the excess liquid off the edge. In this manner the liquid, which is hereinafter referred to as paint but which could also be primer, lacquer, preservative, or any other desired treatment liquid, is not left in drops or puddles on the edge so that a very smooth and uniform coating is achieved.
According to German patent document 4,021,174 filed 3 Jul. 1990 by J. Schiele the liquid is applied to the workpiece edge from a paint-filled chamber that opens via a vertical slit at the vertical edge and vacuum is applied to this chamber to remove the excess paint. This system is an improvement on the arrangement described in U.S. Pat. No. 5,078,080 (citing German patent document 3,740,201) in that it allows the equipment to be somewhat centralized.
The major problem remains that the edge-coating system is a fairly complex installation that must be set up for each particular workpiece type. When workpiece edge profile, height, thickness, width, or shape changes it is necessary to shut down the entire machine, change various parts, and then make numerous adjustments to accommodate the new workpieces.